I use this pedal as the only overdrive pedal at my pedalboard and it does what it needs to do perfectly. Ill go briefly through the channels:
Boost: It boosts your signal as it is meant to do. I rarely turn it more than 9 o'clock as it has quite a range and at around a quarter volume boosts you for maybe 20% .
Crunch: From barely driven to harsh overdrive, you can basically dial any sound you want, except metal
High Gain: This is where you get to metal and beyond. Very good sound, rich harmonics and gain for days. I use this channel for lead playing with gain around 10 o'clock.
You can combine channels, play one at a time or maybe all three together, resulting in huge variety of sounds.
It's solid built and the only thing I find bad about this pedal is it's size but really it saves you space as it combines three pedals in one.